It will depend on the production date of the MC-11 adapters. Recently we started including both the bolts for mounting an X version speakers (longer grade 8 hex head bolt) and for mounting the SC swivel base plate (bevel head stainless steel short bolt)

So if you have a newer adapter or you are ordering them now, they it will include the bolts already.

Sounds like you haven't ordered them yet, so you will be good to go as both sets will be in the box